Journal of Chemical Ecology https://doi.org/10.1007/s10886-019-01085-1 Plant-Based Natural Product Chemistry for Integrated Pest Management of Drosophila suzukii Ian W. Keesey1 & Nanji Jiang2 & Jerrit Weißflog3 & Robert Winz4 & Aleš Svatoš3 & Chen-Zhu Wang2 & Bill S. Hansson1 & Markus Knaden1 Received: 17 April 2019 /Revised: 11 June 2019 /Accepted: 14 June 2019 # The Author(s) 2019 Abstract Since the first reports of damage by Drosophila suzukii, the spotted-wing Drosophila (SWD), over a decade ago in Europe, widespread efforts have been made to understand both the ecology and the evolution of this insect pest, especially due to its phylogenetic proximity to one of the original model organisms, D. melanogaster. In addition, researchers have sought to find economically viable solutions for the monitoring and management of this agricultural pest, which has now swept across much of Europe, North America and Asia. In a new direction of study, we present an investigation of plant-based chemistry, where we search for natural compounds that are structurally similar to known olfactory cues from parasitoid wasps that in turn are well- described ovipositional avoidance cues for many Drosophila species. Here we test 11 plant species across two plant genera, Nepeta and Actinidia, and while we find iridoid compounds in both, only those odorants from Actinidia are noted to be detected by the insect antenna, and in addition, found to be behaviorally active. Moreover, the Actinidia extracts resulted in oviposition avoidance when they were added to fruit samples in the laboratory. Thus we propose the possible efficacy of these plants or their extracted chemistry as a novel means for establishing a cost-effective integrated pest management strategy towards the control of this pest fly. Keywords Olfaction . Chemical ecology . Spotted wing Drosophila . Insect behavior . Parasitoid . Oviposition . IPM Introduction insect has been unrelenting in its invasion and its spread of economic damage within not just Europe (Tait et al. 2018), but Since its identification in Spain and Italy in 2008 (Cini et al. also across North America and Asia (Cloonan et al. 2018). 2012), Drosophila suzukii, the spotted wing Drosophila Since then, a variety of publications have increased our (SWD), has continued to spread and remain a consistent prob- knowledge regarding its chemical ecology (Adrion et al. lem throughout Europe for agricultural and commercial busi- 2014; Crava et al. 2016;Hwangetal.2005; Karageorgi nesses that produce a wide variety of berry fruits or their et al. 2017; Keesey et al. 2015; Ramasamy et al. 2016). associated products. Eleven years later, as of 2019, this pest However, even given the prevalence of D. suzukii as a target Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10886-019-01085-1) contains supplementary material, which is available to authorized users. * Ian W. Keesey 2 State Key Laboratory of Integrated Management of Pest Insects and [email protected] Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing 100101, China * Bill S. Hansson [email protected] 3 Mass Spectrometry/Proteomics Research Group, Max Planck * Markus Knaden Institute for Chemical Ecology, Hans-Knöll-Straße 8, [email protected] D-07745 Jena, Germany 4 The New Zealand Institute for Plant & Food Research, 120 Mt. 1 Department of Evolutionary Neuroethology, Max Planck Institute for Albert Road, Mt. Albert, Auckland 1025, Private Bag 92169, Chemical Ecology, Hans-Knöll-Straße 8, D-07745 Jena, Germany Auckland 1142, New Zealand JChemEcol for research during the last decade, there is still a large gap in for at least some parasitoid species within the Leptopilina applicable technology for monitoring and control of this insect genus, the same compounds seem to also be used as marking pest. pheromones that help to avoid competition for Drosophilid Commercial synthetic production of compounds known to hosts (Pfeiffer et al. 2018). However, again, the commercial be repellent towards the Drosophila genus, such as geosmin synthetic production of these known repellent wasp com- (Stensmyr et al. 2012), are prohibitively expensive to produce pounds is both expensive and labor-intensive, as would be for large-scale usage in the field (Cloonan et al. 2018; the collection of these odors from the mass production of Wallingford et al. 2016a, b), and their application on the fruit parasitoid wasps, which themselves are much smaller than a shortly before harvest (i.e. when D. suzukii mainly infests the single D. melanogaster adult (Ebrahim et al. 2015; Stökl et al. berries) might have a negative impact on fruit quality 2012;). Therefore, collection of these odorants from these tiny (Diepenbrock et al. 2017; Leach et al. 2018). Forinsect pests, Hymenopterans may prove to be too inefficient for large-scale natural-product chemistry, including both microbial-derived production. and plant-derived sources have been shown to be efficient As iridoid compounds that bear strikingly similar structural (Abdel-Sattar et al. 2010; Maia and Moore 2011;Pavela chemistry towards the wasp pheromones have also been de- 2016). For example, the leaves of pepper trees and their ex- scribed in plants like catnip, e.g. Nepeta Lichman et al. 2018; tracts have been used to repel house flies (Musca domestica) Sherden et al. 2018; Shim et al. 2000;), and kiwifruit, e.g. in Ethiopia (Abdel-Sattar et al. 2010), and peppermint oils Actinidia (Lu et al. 2007;Matichetal.2003; Tatsuka et al. have been shown to be repellent towards D. suzukii in a lab- 1990; Twidle et al. 2017), we therefore hypothesized that oratory setting (Renkema et al. 2016). However additional, these plant genera may provide a natural source of functional economically viable strategies to combat D. suzukii still need odorants to repel D. suzukii adults. Commercial products al- to be identified, as most research has focused on attractive ready exist from Nepeta plants, such as dried Nepeta leaves, as odors for monitoring or bait and kill strategies for population well as extracted oils or synthetic compounds that have similar control (Klick et al. 2019; Landolt et al. 2012;). bioactivity to those identified from Nepeta varieties, where all An area of rapidly growing research has been the study of products are sold as cat toys or feline attractants (Bol et al. biocontrol options for D. suzukii using either existing, native 2017). Catnip oil extracts have also been shown previously to parasitoid wasps (e.g. those found in Europe) or other parasit- possess some behavioral repellency against other Dipterans, oids from evolutionary associations within the original habi- such as the stable fly, Stomoxys calcitrans, and other biting tats occupied by D. suzukii (e.g. those parasitoids from China, flies, which are pests of livestock (Zhu 2011). However, to our Korea and Japan). Here, although numerous parasitoid wasp knowledge, no integrated pest management (IPM) strategy species have been examined, there appear to be barriers to the has ever been examined utilizing kiwifruit plant materials. effectiveness of these biocontrol agents (Asplen et al. 2015; In order to test our hypotheses that natural, plant-based Daane et al. 2016), especially due to variation in the immune chemistry may provide possible IPM solutions towards system of D. suzukii and its superior ability to encapsulate D. suzukii, we therefore searched for parasitoid-like iridoid wasp eggs relative to D. melanogaster adults (Chabert et al. compounds in the plant extracts from seven total Nepeta plant 2012; Kacsoh and Schlenke 2012). However, there may still species as well as from four total Actinidia species. In addi- be future success in this tactic, once a suitable species of tion, we tested whether any of these plant-produced odorants parasitoid wasp has been uncovered to more effectively man- could activate the parasitoid-specific olfactory sensory neuron age these flies in natural and agricultural ecosystems. In asso- pathway in the adult fly. Lastly, we sought to examine whether ciation with parasitoids, a study that recently focused on these plant-based odorants were sufficient to induce oviposi- D. melanogaster identified three pheromone components of tional avoidance by D. suzukii adults in the laboratory. the Drosophila-specific parasitoid, Leptopilina boulardi (Hymenoptera: Figitidae: Eucoilinae), where each of the three pheromone components (i.e. iridomyrmecin, nepetalactol, and Methods and Materials actinidine) from the wasp body wash was shown to activate the same parasitoid-specific olfactory sensory neuron (OSN) Plant Sample Extraction Fresh samples of 8 varieties across in D. melanogaster. Moreover, it was shown that this neural 7 species within the Nepeta genus were collected from activation pathway in turn leads to oviposition avoidance of potted plants grown outdoors, including leaves as well as these parasitoid odorants by the adult fly (Ebrahim et al. inflorescences, which were each collected separately. Plant 2015). Importantly, this study also examined behaviors related extracts were generated using 1 hr washes of cut plant to other flies within the genus, including D. suzukii, where the material (2–3 g) in hexane or separately via washes in presence of these three wasp pheromones also generated sig- methanol, and collections were aided by periodic mixing nificant avoidance, both in larvae and adults. Interestingly, (vortex genie 2; www.scientificindustries.com).